a. Field of the Invention
The present invention relates to an ablation method and apparatus, e.g., such as those used for cardiac therapy. More particularly, the present invention pertains to methods that use spectral endocardial analysis for treatment of bradycardias and atrial fibrillation to control and/or provide information regarding ablation processes.
b. Background Art
Catheters for electromagnetic ablation are known and are commonly used to treat various diseases and medical disorders. Typically, the catheter includes an energy-delivering electrode that is coupled to a source of electromagnetic energy, e.g., an electrosurgical generator. Other electrodes can be proximally positioned on the catheter and can be used for sensing and other related electrical purposes.
Also known are steerable catheters. Such catheters include a handle and a deflection mechanism that is operable to effect deflection of the distal end of the catheter in order to facilitate navigation of the catheter through the tortuous pathways of a patient's vasculature.
In prior procedures, an ablation catheter is employed to alter tissue. In order to ablate the tissue, electromagnetic energy is applied to create a lesion via the energy-delivering electrode without regard to the specific level of electromagnetic energy supplied by the generator. In situations where too much electromagnetic energy is delivered to the tissue during the electrosurgical procedure, the tissue “pops”, thus indicating the application of an excessive amount of energy.
Several clinical conditions comprise transitory or permanent autonomic dysfunction by increasing the vagal action and sympathetic driving reduction. As a consequence, transitory or permanent, symptomatic or asymptomatic sinus bradycardias or pauses or transitory AV block may occur. The most typical examples are the cardio inhibitory or mixed neurocardiogenic syncope, carotid sinus syndrome and the functional transitory AV block.
Despite having apparently normal hearts theses patients may be very symptomatic and refractory to conventional medication. Consequently they represent a difficult problem for the cardiologist as far as many of them are referred to the permanent pacemaker implantation. Furthermore we have to add to this group a considerable number of patients presenting a significant sinus and AV node dysfunction with good atropine response suggesting that an important portion of the vagal innervations is still preserved.
A pacemaker has been used, as the last option, to treat the malignant neurocardiogenic syncope. Its indication is uncomfortable in a young and apparently normal heart patient. Furthermore, recent studies have shown the cardiac stimulation has not been a good solution for all the cases of neurocardiogenic syncope. Several studies have shown that a great number of parasympathetic efferent fibers and autonomic ganglia surround the sinus and AV nodes regions.